1. Field of the Invention
This invention relates to novel methods for treating Restless Legs Syndrome (RLS) and related disorders, such as periodic limb movements in sleep (PLMS) and periodic limb movement disorder (PLMD), and for diminishing the occurrence of unwanted limb movements. Particularly, this invention relates to the use of Valeriana, and more particularly to an extract of Valeriana officinalis L., for diminishing the occurrence of unwanted limb movements, either associated with or unassociated with RLS and/or related disorders.
2. Description of the Related Art
The set of conditions known as Restless Legs Syndrome (RLS), also known as Ekbom""s Syndrome following Ekbom""s description of the syndrome in 1944, has been known since at least 1685 (Willis). RLS is a fairly common sensorimotor disorder, yet is not widely recognized by the medical profession or healthcare providers. It is characterized in that it typically gives the individual who suffers from RLS an unpleasant sensation in the legs at rest, causing what is often described as an irresistible desire to move, which generally alleviates the discomfort. (Jones and Deodra, 1997) Also typically, individuals afflicted with RLS experience indescribable crawling sensations in their legs that often occur at night and that are only relieved by moving the legs. (Boucher, 1997) Accordingly, RLS and its related disorders are thought to be a common cause of severe insomnia. (Fox, 1986) RLS is idiopathic in most patients, and has been idenitified as a presenting feature of iron deficiency, and is also common in uremia, pregnancy, diabetes mellitus, rheumatoid arthritis, and polyneuropathy. (O""Keeffe, 1996) PLMD and PLMS, disorders related to RLS, are characterized by episodes of jerking of the limbs, often during periods in which the individual is asleep, and sometimes during periods in which the individual is awake.
RLS affects millions of individuals, having an estimated prevalence of between 1% and 5%. (Wetter and Pollmacher, 1997) Indeed, at least mild symptoms of RLS have been reported to occur in up to 5% of the population of the United States. (O""Keeffe, 1996).
The formal criteria for diagnosis of RLS include: (i) symmetric or asymmetric dysesthesias of the lower, and sometimes also of the upper, extremities; (ii) dysesthesia are typically present at rest, and are especially prevalent at night; (iii) dysesthesia induce a need to move; (iv) movement gives relief, but only for a few seconds. Occasionally, the dysesthesia may be painful. Additional criteria include: (v) involuntary, rhythmic retraction movements occurring especially at night, and especially during sleep stages I and II; (vi) sleep is disrupted and superficial, followed by daytime fatigue. (Grandjean, 1997) Thus, clinical criteria for diagnosis include sleep disturbance, involuntary movements in sleep or wakefulness, a normal neurologic examination, a chronic clinical course, and, in some cases, a positive family history. (Trenkwalder et al., 1996) And the following four minimal criteria for diagnosis have been proposed: (1) desire to move the extremities, often associated with paresthesias/dysesthesias; (2) motor restlessness; (3) worsening of symptoms at rest with at least temporary relief by activity, and (4) worsening of symptoms in the evening or night. (Walters, 1995) The related disorders share some of these characteristics.
The underlying cause of RLS and its related disorders is not clearly known. However, it has been observed that the frequency of occurrence increases with advancing age. In most individuals with RLS, the results of complete blood cell counts and iron, ferritin, folate, and vitanin B12 levels are normal. No hematologic or chemical abnormalities are associated with individuals who experience periodic movements during sleep who also do not have RLS (Krueger, 1990).
Regarding the etiology of RLS and related disorders, pathophysiologically it has been reported that a malfimction of dopamine and opiate receptors in the central nervous system are associated with RLS and related disorders. (Grandjean, 1997) And while the precise aetiology of RLS and PLMS are unknown, it has been reported that periodic leg movements result from a suprasegmental disinhibition of descending inhibitory pathways. An evaluation of the efficacy of certain drugs revealed that, according to one study, the dopaminergic, adrenergic and opiate systems play a major role in the pathogenesis of RLS/PLMS. In spite of this association, therapy of RLS and PLMS remains symptomatic except for some secondary forms. (Wetter and Pollmacher, 1997) Indeed, one study has reported that xe2x80x9c[w]hile the Dopamenergic CNS pathways have been thought to be the primary neurotransmitter involved, the opioids secondary, there is mounting evidence that the situation is far more complicated, that many neurotransmitters, including stimulating and inhibiting amino acids, play a part.xe2x80x9d (Williams, 1996).
Currently, RLS is typically treated by drugs such as clonazepam, narcotics, dopamine agonists, benzodiazipines, clonidine, gabepentin, (Joy, 1997; Wetter and Pollmacher, 1997; Trenkwalder et al., 1996) and magnesium (Hornyak et al., 1998), and typically via oral administration. Currently, one popular pharmaceutical treatment of RLS in the United States is pramipexole, known by the trade name Mirapex, [available from Phannacia and Upjohn] which has been reported to cause major side effects including insomnia, and dizziness. For example: xe2x80x9cIn pramipexole recipients with early disease, the most commonly experienced adverse events were nausea, dizziness, somnolence, insomnia, constipation, asthenia and hallucinations.xe2x80x9d (Dooley M, Markham A, Pramipexole. A review of its use in the management of early and advanced Parkinson""s disease, Drugs Aging 1998 Jun;12(6):495-514); xe2x80x9cThe most common adverse events ( less than 10%) were dizziness, insomnia, nausea, and postural hypotension.xe2x80x9d (Wermuth L, A double-blind, placebo-controlled, randomized, multi-center study of pramipexole in advanced Parkinson""s disease, Eur J Neurol 1998 May;5(3):235-242); xe2x80x9cIn the assessment of adverse events, nausea, insomnia, constipation, somnolence, and visual hallucinations occurred more frequently in the pramipexole treatment group compared with placebo patients.xe2x80x9d (Shannon K M, Bennett J P Jr, Friedman J H, Efficacy of pramipexole, a novel dopamine agonist, as monotherapy in mild to moderate Parkinson""s disease. The Pramipexole Study Group. Neurology 1997 Sep;49(3):724-8).
Therefore, there exists a need for an effective, alternative treatment and related treatment regime options for individuals who are afflicted with RLS and/or its related disorders. More particularly, there exists a need for treatments that do not induce the unwanted effects observed in modern therapeutics for Restless Legs Syndrome (RLS) and related disorders.
A novel method of inhibiting at least one symptomology of Restless Legs Syndrome (RLS) and its related disorders is disclosed. Said method comprises identifying a host afflicted with Restless Legs Syndrome (RLS) or a related disorder; and administering to said host a pharmaceutically effective amount of Valeriana. The Valeriana is preferably an extract, and more preferably an extract of Valeriana officinalis L. The host is preferably a mammal, and may also preferably be a canine, feline, or member of the Class Rodentia. The method of the present invention may be used to treat a host in order to diminish undesired limb movements, and may involve the administration of a particular compound, found in the above-mentioned extracts, preferably selected from the group consisting of 10(14)-Aromadendren-4-ol, 6,10(14)-Guaiadien-4-ol, Valerenal, Valerenol, Valerenic acid, Acetoxyvalerenic acid, Hydroxyvalerenic acid, and mimetics thereof, and may involve the administration of a combinations of these particular compounds and mimetics thereof.